I cna't see how... The I/O backplane is a little board, about 5" square. It contains 4 edge connectors only (no other componets, not even decoupling capacitors), and has edge fingers along the bottom edge that fit into a simialr connector on the main backplane (the large PCB, also jsut connectors, that's flat in the vottom of the machine). In this cae, somebody careffully desoldered the second-from-top connector on the backoplane. I assume they needed the connector for soemthing -- otherwiswe qwhy not just whip out the complete I/O backplane if it was causing problems (the machine will run without it). I suppose a previous owner might have had a Peripheral Control ROM and used interfaces with this machine (and this was later separated from the machine), and that one connector on the I/O backplane might have become damaged and, say, been shorting a couple of lines together so it had to be removeed I guess I'll never know (and I don't really need to know -- I just need to get the replacement connector and solder it in). -tony